Mode dial

A mode dial or camera dial is a dial used on digital cameras to change the camera's mode. Most digital cameras, including dSLR and SLR-like cameras, support modes, selectable either by a dial or from a menu. On point-and-shoot cameras which support modes a range of scene types is offered. On dSLR cameras and SLR-like cameras, mode dials usually offer access to manual settings. The more compact point-and-shoot cameras, and cameras offering a great many modes, do not have mode dials, using menus instead. Some SLR lenses themselves offer control over things such as aperture, reducing the need for mode support in the camera body.


Generic mode dial for digital cameras showing some of the most common modes. (Actual mode dials can vary from camera to camera. For example, point-and-shoot cameras don't often have manual modes.) Manual modes: Manual (M), Program (P), Shutter priority (S), Aperture priority (A). Automatic modes: Auto, Action, Portrait, Night portrait, Landscape, Macro.

Location of the dial
On most dSLRs and SLR-like cameras, the mode dial is located at the top of the camera, to one side of the flash/viewfinder hump. On point-and-shoot cameras, however, the mode dial's location is less standard. On many models, it is found on top like dSLRs. On other point-and-shoots, the dial is found on the back of the camera, often coupled with a menu-navigation button.


A Kodak dSLR with the mode dial located near the flash/viewfinder hump.

Modes
Various camera types and specific cameras have different modes. On dSLRs, these usually contain manual settings and a small sample of automatic modes. SLR-like cameras usually have manual modes and several automatic scene modes. On point-and-shoot cameras, all manual control may be condensed into one mode (e.g. ASP, for Aperture priority, Shutter priority, Program) or completely absent. Compact cameras also generally have a large array of scene modes. Point-and-shoot and SLR-like digital cameras usually have a movie mode to capture videos, though the design of dSLRs prevents these cameras from having movie modes as well.

Manual modes
Manual modes include:

* P: Program mode offers partial control over shutter speed and aperture.
* Tv or S: Shutter priority controls the shutter speed, and aperture is calculated by the camera.
* Av or A: Aperture priority controls the aperture, and the shutter is calculated by the camera.
* M: Manual mode controls shutter speed and aperture independently.

Automatic scene modes
In automatic modes the camera determines all aspects of exposure, choosing exposure parameters according to the application within the constraints of correct exposure, including exposure, aperture, focussing, light metering, white balance, and equivalent sensitivity. For example in portrait mode the camera would use a wider aperture to render the background out of focus, and would seek out and focus on a human face rather than other image content. In the same light conditions a smaller aperture would be used for a landscape, and recognition of faces would not be enabled for focussing.

Some cameras have tens of modes. Many cameras do not document exactly what their many modes do; for full mastery of the camera one must experiment with them.

In general:

* Action or sport mode increases ISO and uses a fast shutter speed to capture action.
* Landscape mode uses a small aperture to gain depth of field.
* Portrait mode widens the aperture to throw the background out of focus. The camera may recognise and focus on a human face.
* Night portrait mode uses an exposure long enough to capture background detail, with fill-in flash to illuminate a nearby subject.

Other scene modes found on many cameras include Fireworks, Snow, Natural light/Night snapshot, Macro/Close-up, and Movie mode.


Source : http://en.wikipedia.org/wiki/Mode_dial